The present invention concerns a dialysis machine, particularly for home use, comprising a dialyzer, for example, a hollow fiber type dialyzer, with a first blood circulation inlet and a first blood circulation outlet, a dialysate supply means, an arterial line connected between the patient""s arteriovenous fistula and said first dialysis inlet, a venous line connected between said arteriovenous fistula and said first dialyzer outlet, a pump associated with said artery line, a dialysate inlet line connected between said dialysate supply means and a second dialyzer inlet, and a dialysate evacuation line connected between the dialysate collection container and a second dialysis outlet.
Chronic dialysis traditionally requires large quantities of dialysate. Approximately 120 liters of dialysate are necessary for proper diffusion exchange at the dialyzer membrane in order to purify the patient""s blood.
Dialysis is currently performed three times a week in a hospital for about four hours and requires complex machinery, particularly water treatment equipment to provide water of sufficiently high quality in terms of mineral level and bacterial count. This purified water is added to a concentrate to make the amount of dialysate needed. Despite this, and despite daily disinfection of the dialysis machines, the risk of contamination remains high.
The fact that the patient is treated for relatively long periods of time is a major inconvenience. The patient becomes hypercatabolic between sessions, and treatment necessitates a long, tiring intervention and complex equipment, primarily due to the large quantities of dialysate to be prepared. The machinery that performs hemodialysis in hospital settings is very cumbersome and impossible for an non-qualified person to use. For these reasons it is very difficult to allow a patient connect himself or herself without assistance and medical supervision. Current equipment is so complex that technicians must always be nearby for maintenance.
Dialysis machines of the type described in the preamble for home use are known in the art, particularly in U.S. Pat. No. 4,950,395. This document describes a very elementary dialysis apparatus which operates on the basis of gravity and blood pressure, with a pump attached in series on the dialysate inlet line. The apparatus has grip or clamps attached to the various lines to regulate flow during the dialysis session using a flowmeter. There are considerable variations in dialysate flow between the beginning and the end of the session, which has a marked effect on dialysis performance. Moreover, regulating the flow is relatively difficult; the assistance of a third person is required.
International application published as No. WO-95 20 985 concerns a dialysis apparatus mainly consisting of a chamber, a reversible pump to pressurize or depressurize the chamber, a heated pouch for sterile dialysate, and a used dialysate evacuation pouch placed inside the chamber and joined with a T connector to a catheter connected to the peritoneum of the patient. A valve device permits the flow of liquid to be selectively established between the catheter and one of the pouches. When the pouch is depressurized, sterile dialysate flows into the heated pouch from the supply pouches, and used dialysate is evacuated from the patient into the evacuation pouch. When the chamber is pressurized, sterile, heated dialysate flows into the patient from the heated pouch and used dialysate flows into a collection container. However, this dialysis apparatus is designed only for use in peritoneal dialysis.
U.S. Pat. No. 4,132,644 has as its object a dialysis machine which recycles used dialysate using a peristaltic pump to generate dialysate flow and which requires regulation of dialysate flow during the session. The dialysate supply pouch is located inside a chamber sealed with variable pressure to modify pressure within the pouch and in the circuit, thereby regulating dialysate flow. This apparatus is difficult to use correctly and requires the assistance of a qualified person.
U.S. Pat. No. 4,386,634 has as its object an apparatus and a technique for preparing dialysate.
The present invention proposes overcoming the various disadvantages for chronic dialysis mentioned above by eliminating long treatment sessions in a hospital setting and substituting much shorter, daily sessions using smaller quantities of dialysate packaged in sterile bags, thereby eliminating the risk of the patient becoming hypercatabolic between two dialysis sessions; these sessions can take place at home without any medical assistance or supervision, as the dialysis machine can be operated without any complex manipulations. Another aim of the invention is to provide a simple, reliable dialysis machine, especially for use in acute dialysis where treatment is continuous, and also for performing hemodiafiltration when the machine is used for either chronic dialysis or acute dialysis.
These objectives are met by a dialysis machine such as the machine described in the preamble, characterized in that said dialysate supply means comprises at least one chamber in which there is at least one pouch containing sterile dialysate, said pouch being connected to said dialysate inlet line leading to the dialyzer, and a means for pressurizing said pouch to provoke the flow of dialysate into said inlet line.
According to a preferred embodiment of the dialysis machine used for acute dialysis, said supply means comprises at least two chambers, each containing at least one pouch of sterile dialysate, said two pouches being capable of separate pressurization by said pressurizing means, and at least two reserve pouches of sterile dialysate located outside said chambers, each connected to one of said respective pouches by a conduit. Said dialysis machine advantageously comprises a system for alternately clamping these conduits.
According to a particular embodiment of the dialysis machine used for hemodiafiltration, said supply means consists of at least one pouch of sterile dialysate located in a chamber and connected with an inlet line to said venous line.
Said pressurizing means preferably consists of at least one gas reservoir connected to said chamber. There may be at least one air compressor.
It is advantageous for said inlet line to be calibrated so that when there is a given pressure in the chamber, the liquid will flow at a constant given rate.
Preferably the dialysate inlet line leading to the dialyzer is calibrated so that when there is a predetermined pressure in the chamber, the dialysate will flow at a rate ranging essentially from 100 to 500 ml/minute and preferably from 100 to 250 ml/minute.
The dialysate inlet line advantageously has a flow restrictor to generate a predetermined loss of charge. This inlet line may consist at least partially of a reinforced calibrated tube having a constant section along a predetermined length.
According to a particular embodiment of the dialysis machine designed for hemodiafiltration, said pressurizing means advantageously maintains an interior pressure within the chamber that is sufficient to provoke the flow of dialysate through the inlet lines to a bubble trap and to the dialyzer, respectively. The inlet lines preferably are calibrated so that for a given predetermined pressure in the chamber, the liquid will flow at a constant given rate.
It is advantageous for the dialysis machine to comprise a volumetric device connected to the evacuation line and joining the second outlet of the dialyzer with the dialysate collection container. Said volumetric device may be a dialysate pump with an adjustable flow rate.
According to a preferred construction, the dialysis machine comprises a frame with a housing for said dialyzer, at least one chamber containing at least one pouch of sterile dialysate, said arterial line connected between the patient""s artery and said first dialyzer inlet, said venous line connected between the patient""s vein and said first dialyzer outlet, said pump coupled to said artery line, said sterile dialysate inlet line connected between said pouch of sterile dialysate and the second dialyzer inlet, said dialysate collection container, said dialysate evacuation line connected between said second dialyzer outlet and said collection container, said means for pressurizing the sterile dialysate pouch located within said chamber, and a folding cover attached to the frame.
According to a particular form of the dialysis machine designed for performing acute dialysis, said housing surrounds the two chambers which each contain at lest one pouch of sterile dialysate and said dialysis machine comprises a support integral with the frame for holding the pouches of reserve sterile dialysate. The support for the reserve pouches may consist of the cover.